Motor winding wire for a hydrocarbon application

ABSTRACT

A motor winding wire. The motor winding wire may be configured for use in, and direct exposure to, a hydrocarbon environment. The motor winding wire may be electrically insulated by one polymer layer, whereas another, outer, polymer layer is employed to provide moisture resistance as well as other contaminant and hydrocarbon environment shielding to the underlying layer. Additionally, this manner of polymer layering over the motor winding wire is achieved in a manner cognizant of the limited dimension of the motor winding wire.

CROSS REFERENCE TO RELATED APPLICATION(S)

This Patent Document claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application Ser. No. 60/889,650, entitled Motor WindingWires for Oilfield Application, filed on Feb. 13, 2007, which isincorporated herein by reference.

FIELD

Embodiments described relate to equipment for placement within ahydrocarbon well. In particular, embodiments of equipment employingmagnetized motor winding wires are described wherein the equipment maybe configured for placement and relatively continuous use within thewell over an extended period of time, perhaps between about 1½ and 5years.

BACKGROUND

A variety of hydrocarbon applications involve the use of electricallypowered equipment disposed within a hydrocarbon well for extendedperiods of time. For example, an electric submersible pump (ESP) may bepositioned within a hydrocarbon well to promote the extraction ofhydrocarbons from the well. In such circumstances it may be preferableto leave the pump in place and operating throughout the hydrocarbonproduction from the well. Thus, depending on the hydrocarbon reservoiritself and the parameters of the operation, the pump may be leftoperating and in place for up to about 5 years or longer.

Equipment such as the indicated ESP may include several componentssusceptible to damage upon exposure to the downhole conditions of thewell. For example, the moisture content, chemical makeup, and pressureor temperature extremes of the downhole environment may tend to degradecertain components of the ESP over time. Components of the ESPsusceptible to such exposure may include a power cable and motor partssuch as motor windings or conductors. However, measures may be taken tohelp shield such components from the downhole environment. For example,in the case of the power cable, thick and robust, moisture resistantpolymer layers may be extruded over an electrically conductive core. Inthis manner the core may remain substantially unaffected by downholeconditions so as to help ensure that the cable remains operation for anextended period. Alternatively, in the case of the motor and windings,they may be housed within an oil-filled and hermetically sealed casingisolated from the environment of the well.

Unfortunately, the oil filled casing noted above invariably fails tomaintain complete isolation from the conditions in the surroundingdownhole environment. For example, when left within the well for anextended period, moisture and chemical contaminants from the downholeenvironment are eventually able to seep through and penetrate the casingto some degree. Nevertheless, in the case of some parts of the motor,the fact that the casing remains predominantly oil-filled may be enoughto avoid failure. For example, the moving parts of the motor may remainin the presence of sufficient lubrication to remain operational in spiteof a degree of moisture and chemical contaminants. However, as describedbelow, the direct exposure of the motor windings to the wellcontaminants, especially moisture, may be enough to render themineffective, leading to malfunction of the entire ESP.

Unlike other parts of the motor, motor winding wires are not dependentupon the presence of sufficient oil concentration within the casing inorder to remain operational. Rather, like the power cable, it is thesubstantial shielding of the motor winding wires from direct contactwith downhole contaminants, especially moisture, which may be key toensuring continued functionality of the wires. However, as indicatedabove, given enough time downhole, the casing is likely to be penetratedby such downhole contaminants leaving the wires directly exposed tocontaminants.

In order to further shield the motor winding wires from direct exposureto downhole contaminants, polymer layers may be provided about theconductive core of the motor winding wires. Thus, in theory, the polymerlayers may provide a degree of shielding to the motor winding wiressimilar to the power cable configuration noted above. Unfortunately,however, the dimensions and properties of the motor winding wiresthemselves render conventional polymer layering and shieldingineffective for prolonged protection of the wires from exposure todownhole contaminants. For example, a conventional motor winding wiremay be magnetized wire core of no more than about 5 gauge copper wire,generally between about 16 and 50 gauge. Furthermore, the motor windingwire may be configured for relatively tight windings. As such, no morethan between about 0.25 to 20 mil polymer layers may be effectivelyprovided over the wires. In fact, for 30 gauge or so windings andsmaller, as a matter of practicality it may be more effective to bypassextruding the polymer layer altogether and simply varnish the polymerover the wound wires to provide the shielding from downholecontaminants. Regardless, the polymer layer may be of limited thicknessand effectiveness.

In addition to the limited thickness, the effectiveness of the polymerlayer as a shield from downhole contaminants may be further limited bythe particular types of polymers available for use with motor windingwires. That is, given the small dimension and the conductive nature ofmotor winding wire, materials disposed thereabout may be of anelectrically insulating character to ensure proper wire operation. Thesematerials may include polyimide, polyester, polyamide,poly-ether-ether-ketone and other conventional electrical insulators.Unfortunately, however, such insulators are prone to hydrolyticdegradation or moisture absorption upon prolonged direct exposure toeven a small degree of moisture and other downhole contaminants. As aresult, the motor winding wire as well as the entire ESP or otherequipment employing such winding wire is prone to fail, generally wellin advance of about 5 years. In fact, smaller ESP motors positioneddownhole for continued use often display a lifespan of no more thanabout 1 year. Furthermore, efforts to overcome polymer shieldinglimitations via over-wrapping or enamel layer configurations remaininsufficient to prevent such hydrolytic degradation and moistureabsorption.

SUMMARY

A motor winding wire is provided for an application in a hydrocarbonenvironment such as the downhole environment of a well. The wireincludes a conductive core with an electrically insulating polymer layerthereabout. A moisture resistant outer polymer layer is provided aboutthe electrically insulating polymer layer for shielding it from moisturein the environment.

In one embodiment, a tie layer may be disposed between the electricallyinsulating polymer layer and the moisture resistant outer polymer layer.The tie layer may include a polymer of one of the outer polymer layerand the electrically insulating polymer layer along with an adhesivefunctional group to provide bonding between the outer and electricallyinsulating polymer layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view of a well with an embodiment of anelectrically driven assembly disposed therein.

FIG. 2 is an enlarged cross-sectional view of an electric motor of theassembly and the well of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of an embodiment of a motorwinding wire of the electric motor of FIG. 2.

FIG. 4 is cross-sectional view of an alternate embodiment of a motorwinding wire.

FIG. 5 is an enlarged view of the motor winding wire of FIG. 4 takenfrom 5-5.

FIG. 6 is a partially cross-sectional overview of an embodiment of anelectrically driven assembly within a well at an oilfield.

DETAILED DESCRIPTION

Embodiments are described with reference to certain types of motorwinding wires for use with electrical equipment for hydrocarbonapplications. In particular, focus is drawn to equipment in the form ofelectric submersible pumps employed within hydrocarbon wells. However, avariety of electrical equipment may employ embodiments described herein,particularly where the equipment is intended for long term and/orcontinuous use while exposed to a harsh or moisture rich hydrocarbonenvironment.

Referring now to FIGS. 1 and 2, an embodiment of an electrically drivenassembly 100 is depicted disposed within a hydrocarbon well 180. Thewell 180 is defined by a casing 150 through a formation 190 at anoilfield. In the embodiment shown, the assembly 100 is electronicallydriven equipment in the form of an electric submersible pump (ESP).However, other types of electrically driven equipment may be employedwithin such a well 180. As shown, the ESP assembly 100 includes anextraction line 160, a pump 140, and an intake region 130, as well as amotor 125 powered by a cable 175. The ESP assembly 100 may operate byrotation of a motor assembly 200 within a casing 225 of the motor 125.The motor 125 may be employed to power the pump 140 to draw inhydrocarbon fluids from the environment of the well 180. Such fluids maythen be driven up the extraction line 160 to the well surface.

The above-noted assembly 100 may be disposed within the well 180 forcontinuous operation over an extended period of time. For example, anESP assembly 100 may be disposed within the well 180 as shown forsubstantially continuous use throughout the productive life of the well180. In most cases, this may be between about 2 and 5 years, or longer.For this period, the assembly 100 may be subjected to harsh wellconditions such as extreme temperatures or pressures, and exposed tocontaminants 110 such as moisture and corrosive chemicals. Nevertheless,the assembly 100 may remain functional throughout the substantialduration of the productive life of the well 180. In particular, asdetailed below, motor winding spools 210 of the assembly 100 may besufficiently shielded from contaminants 110 of the well 180 so as toavoid operational failure of the assembly 100 during the productive lifeof the well 180.

Continuing with reference to FIGS. 1 and 2, the assembly 100 is directlyexposed to the environment of the well 180 which includes theabove-noted contaminants 110. With reference to FIG. 2, a casing 225 ofthe motor 125 may be hermetically sealed to provide a degree ofprotection from the indicated contaminants 110. Nevertheless, at somepoint during the life of the well 180, contaminants 110 may reach anoil-filled space 250 within the casing 225. Thus, the rotatable motorassembly 200 being located within the oil-filled space 250 may bedirectly exposed to such contaminants 110. Of particular note, motorwinding wire 201 of motor winding spools 210 may come into directcontact with contaminants 110 such as moisture. However, as detailedbelow, the electrical conductivity of the motor winding wire 201 mayremain substantially unaffected by contact with moisture contaminants110. Thus, failure of the motor 125 and thus, the entire ESP assembly100 may be avoided. Furthermore, while the spools 210 are shown disposedwithin an ESP assembly 100, other motorized assemblies may employ motorwinding wire 201 as noted below. Such assemblies may include downholetractor assemblies, powered centralizers, perforation guns, samplingtools and a host of other assemblies that may be motorized.

Referring now to FIG. 3, with added reference to FIG. 2, embodiments ofmotor winding wire 201 may be configured and constructed so as to avoidcontaminant 110 contact with a conductive core 300 of the wire 201. Inthis manner, the conductive nature of the core 300, generally magnetizedcopper, may remain unaffected by contaminants 110 otherwise prone todiminish conductivity. In particular, the conductive core 300 may beshielded by a tailored combination of polymer layers 350, 375 asdescribed below.

In order to provide corona discharge resistance and electrically isolatethe conductive core 300, an insulating polymer layer 350 may be providedthereabout. The insulating polymer layer 350 may be of a variety ofpolymer types conventionally used for electrically insulating winding ormagnet wires and provided in a variety of manners. For example, wherethe motor winding wire 201 is larger than about 18 gauge, the insulatingpolymer may be extruded to more than about 2 mils in thickness over thecore 300 to form the layer 350. Alternatively, for smaller winding wire201, an enamel coating or varnishing process may be employed to provideless than about 2 mils of insulating polymer over the core 300, therebyforming the insulating polymer layer 350. Additionally, other techniquesfor providing the layer 350 may be employed such as use of an adhesivetape form of the insulating polymer, with the adhesive type selectedbased on downhole temperature extremes likely to be encountered withinthe well 180.

Materials for the insulating polymer layer 350 when provided byextrusion or in the form of a polymer tape may include a polyimide,polyester, polyesterimide, polyamide-imide, polyamide,poly-ether-ether-ketone, polyethylene terephthalate, polyphenylenesulfide, and a self-reinforced polyphenylene. Alternatively, where theabove described technique of varnishing is employed, the insulatingpolymer layer 350 may more preferably be a polymeric imide, ester,ester-imide, ester-amide, amide-imide, urethane or an epoxy.Additionally, the polymeric or epoxy material may be filled withnano-scale particles configured to improve durability and/or insulatingcharacteristics of the insulating polymer layer 350.

Continuing with reference to FIG. 3, with added reference to FIGS. 1 and2, the insulating polymer layer 350 may provide sufficient electricalinsulation and corona discharge protection. However, an additionalmoisture resistant outer polymer layer 375 may be provided over theinsulating polymer layer 350 so as to prevent contaminants 110 such asmoisture from reaching the insulating polymer layer 350. In this manner,an insulating polymer may be selected for the underlying insulatingpolymer layer 350 without significant concern over contaminants 110within the well 180. In particular, the material for the insulatingpolymer layer 350 may be selected without significant concern overhydrolytic degradation thereof. That is, the outer polymer layer 375 maybe configured to shield the insulating polymer layer 350 from moisturewithin the well 180. Thus, electrically insulating polymers, perhapseven those otherwise susceptible to hydrolytic degradation upon exposureto moisture, may nevertheless be employed in forming the insulatingpolymer layer 350. As a result, a greater degree of flexibility may beexercised in selecting the proper insulating polymer for electricalisolation of the underlying core 300.

In addition to shielding the underlying insulating polymer layer 350,the outer polymer layer 375 may be configured without significant regardto providing electrical insulation to the core 300. Thus, polymers forthe outer polymer layer 375 may be selected with focus on moistureresistance, corrosive chemical resistance or other contaminant shieldingcharacteristics.

In one embodiment, the outer polymer layer 375 may be particularlyconfigured based on downhole temperatures within a well 180 such as thatof FIGS. 1 and 2. For example, the outer polymer layer 375 may beconfigured to withstand high-temperature downhole conditions exceedingabout 300° C. In such an embodiment, the outer polymer layer 375 may beconfigured of a fluoropolymer. For example, anethylene-tetrafluoroethylene copolymer may be employed, perhaps amendedwith an adhesive functional group to promote adhesion to the insulatingpolymer layer 350 may be employed. Maleic anhydride, acrylic acid,carboxyl acid, or silane, may serve as such an adhesive group. Othersuitable high temperature resistant materials for the outer polymerlayer 375 may include polychlorotrifluoroethylene or ethylenechlorotrifluoroethlyene which may similarly be amended with an adhesivegroup as described. Additionally, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene,expanded-polytetrafluoroethylene (ePTFE), and any improvedfluoropolymers may be employed to form the outer polymer layer 375.

In another embodiment, the outer polymer layer 375 may be configured forlower temperature applications at below about 300° C. and of apolyolefin such as polyethylene, polypropylene, ethylene-propylenecopolymer, poly(4-methyl-1-pentene), and a polyolefin elastomer. Again,these materials may be amended with maleic anhydride, acrylic acid,carboxyl acid, silane or other suitable material to promote adhesion tothe underlying electrically insulating polymer layer 350.

As with the insulating polymer layer 350, a variety of techniques mayalso be employed to deliver the outer polymer layer 375. That is,depending on wire sizing, the outer polymer layer 375 may be extruded,perhaps even co-extruded with the insulating polymer layer 350. In oneembodiment the outer polymer layer 375 is processed down to about 1 milfollowing the extrusion. Alternatively, the outer polymer layer 375 maybe sintered over the insulating polymer layer 350 by conventionaltechniques. Additionally, an adhesive tape form of the outer polymer maybe employed to provide the outer polymer layer 375 over the insulatingpolymer layer 350.

Referring now to FIG. 4, an alternate embodiment of a motor winding wire400 is depicted. Of particular note is the fact that the wire 400includes an additional tie layer 465 disposed between its outer polymerlayer 480 and its insulating polymer layer 450. The tie layer 465 may beemployed to serve as an adhesive layer between the outer polymer layer480 and underlying insulating polymer layer 450 so as to ensure adequatebonding therebetween. As detailed below, the tie layer 465 may beparticularly advantageous in maintaining such a bond given the differenttypes of materials employed for the outer polymer layer 480 versus theunderlying insulating polymer layer 450. Ensuring adequate bonding inthis manner may be beneficial to the performance and life of an electricmotor 125 in a harsh downhole environment such as that of FIG. 1.

Continuing with reference to FIG. 4, the insulating polymer layer 450may be configured for electrically insulating a conductive core 425 ofthe wire 400. Thus, the insulating polymer layer 450 may be made ofmaterials such as those detailed above for the insulating polymer layer350 of the motor wire 201 of FIGS. 2 and 3. Additionally, the outerpolymer layer 480 may be configured to provide contaminant resistance tothe underlying portions of the wire 400, for example, to moisture. Thus,again, the materials employed for the outer polymer layer 480 may bethose detailed above with reference to the outer polymer layer 375 ofthe wire 201 of FIGS. 2 and 3. However, given the generally differentpurposes of the insulating polymer layer 450 as compared to the outerpolymer layer 480, the tie layer 465 may be provided to ensure adequatebonding of the layers 450, 465, 480 to one another.

Continuing with reference to FIG. 5, an enlarged view of section 5-5 ofFIG. 4 is depicted. In particular, the tie layer 465 is shown betweenthe outer polymer layer 480 and the insulating polymer layer 450 asdescribed above. So as to ensure compatibility and bonding to both theother layers 450, 480, the tie layer 465 is made up of a main chain orbase polymer of one of the adjacent layers 450, 480 with a functionalgroup 500 disbursed therein having an adhesive character relative to theother of the layers 450, 480. In this manner, the base polymer of thetie layer 465 may provide for adhesion of one adjacent layer 450, 480 tothe tie layer 465 while the functional group 500 provides adhesion tothe other.

A variety of base polymers may be employed for the tie layer 465depending on the materials of the adjacent insulating polymer layer 450and outer polymer layer 480. For example, polyethylene, polypropylene,ethylene-propylene copolymer, poly(4-methyl-1-pentene),ethylene-tetrafluoroethylene copolymer, ethylene fluorinatedethylene-propylene terpolymers, polychlorotrifluoroethylene, ethylenechlorotrifluoroethlyene, as well as a host of other fluoropolymers maybe employed as the base polymer of the tie layer 465. Maleic anhydride,acrylic acid, carboxyl acid, silane or other suitable functional group500 may similarly be employed to serve as an adhesive relative to one ofthe layers 450, 480 adjacent the tie layer 465.

By way of example, with reference to the above listed material choicesfor the tie layer 465, one embodiment of a motor winding wire 400 asdepicted in FIG. 4 may include an electrically insulating polymer layer450 of polyamide material whereas the contaminant resistant outerpolymer layer 480 may be of ethylene-tetrafluoroethylene copolymer. Insuch an embodiment, the tie layer 465 may be made up ofethylene-tetrafluoroethylene copolymer as its base polymer for adhesionto the outer polymer layer 480. In this example a functional group 500of, for example, maleic anhydride may be present throughout the tielayer 565 as depicted in FIG. 5 to provide adhesion to the underlyinginsulating polymer layer 450.

Continuing with reference to FIGS. 4 and 5, manufacture of the depictedmotor winding wire 400 may be according to techniques described aboverelative to the insulating polymer layer 450 and the outer polymer layer480. Providing of the intervening tie layer 465 is preferably achievedby extrusion. In fact, in one embodiment each of the layers 450, 465,480 is simultaneously co-extruded about the conductive core 425 to formthe wire 400.

Referring now to FIG. 6, an embodiment of a contaminant resistantelectrically driven assembly 600 in the form of an ESP is depictedwithin a well 680 at an oilfield 645. The well 680 is positioned belowconventional surface equipment 625 at the oilfield 645 and equipped witha casing 650 traversing various portions 655, 660 of a formation. Thewell 680 ultimately provides access to a production region 675 where theESP assembly 600 may be positioned for long term operation exceedingabout 2 years and perhaps throughout the productive life of the well680.

Resistance to moisture, harsh chemicals, and other potentialcontaminants 610 is provided to motor winding wires of the ESP assembly600 according to configurations and techniques detailed above. Thus, inspite of the potentially harsh moisture rich downhole conditions,embodiments of the ESP assembly 600 may be left in place without undueconcern over the possibility of pump failure. In this manner, expensesassociated with well shut down and pump replacement may generally beavoided.

Embodiments described hereinabove include motor winding wires, which, inspite of limited dimension, may be provided with adequate electricalinsulating along with sufficient polymer shielding so as to allow fortheir direct exposure to moisture and other hydrocarbon contaminantswithout undue risk of premature failure. In fact, equipment employingsuch motor winding wires may be positioned downhole in a hydrocarbonwell and operated continuously for the substantial life of the wellwithout serious concern over equipment breakdown due to motor windingwire failure.

The preceding description has been presented with reference to presentlypreferred embodiments. However, other embodiments not detailedhereinabove may be employed. For example, a motor winding wireconstructed of materials and according to techniques detailedhereinabove may be employed in conjunction with powering of a downholetractor, powered centralizer, perforation gun, sampling or otheroilfield tools aside from an ESP. Persons skilled in the art andtechnology to which these embodiments pertain will appreciate that stillother alterations and changes in the described structures and methods ofoperation may be practiced without meaningfully departing from theprinciple, and scope of these embodiments. Furthermore, the foregoingdescription should not be read as pertaining only to the precisestructures described and shown in the accompanying drawings, but rathershould be read as consistent with and as support for the followingclaims, which are to have their fullest and fairest scope.

1. A motor for use within a hydrocarbon wellbore, the motor comprising:a hermetically sealed casing containing an oil-filled space; at leastone spool of motor winding wire disposed within the oil-filled space ofthe casing and comprising: a conductive core; an electrically insulatingpolymer layer about said conductive core; and a contaminant resistantouter polymer layer about said electrically insulating polymer layer. 2.The motor of claim 1 wherein the hydrocarbon application is a downholewell application and said outer polymer layer is contaminant resistantto one of moisture and a corrosive chemical in the wellbore.
 3. Themotor of claim 1 wherein said insulating polymer layer is of a materialselected from a group consisting of a polyimide, polyester,polyesterimide, polyamide-imide, polyamide, poly-ether-ether-ketone,polyethylene terephthalate, polyphenylene sulfide, a self-reinforcedpolyphenylene, polymeric imide, polymeric ester, polymeric ester-imide,polymeric ester-amide, polymeric amide-imide, polymeric urethane, and anepoxy.
 4. The motor of claim 1 wherein said outer polymer layer is of amaterial selected from a group consisting of anethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene,ethylene chlorotrifluoroethlyene, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene,expanded-polytetrafluoroethylene (ePTFE), any improved fluoropolymers,polyethylene, polypropylene, ethylene-propylene copolymer,poly(4-methyl-1-pentene), and a polyolefin elastomer.
 5. The motor ofclaim 1 wherein the hydrocarbon application is a downhole wellapplication at a temperature exceeding about 300° C. and said outerpolymer layer is of a fluoropolymer configured to withstand thetemperature exceeding about 300° C.
 6. The motor of claim 1 wherein thehydrocarbon application is a downhole well application at a temperatureless than about 300° C. and said outer polymer layer is of a polyolefin.7. The motor of claim 1 further comprising a tie layer disposed betweensaid electrically insulating polymer layer and said outer polymer layer,said tie layer comprising a polymer of one of said electricallyinsulating polymer layer and said contaminant resistant outer polymerlayer and an adhesive functional group for bonding therebetween.
 8. Themotor of claim 1 wherein said at least one spool of motor winding wirecomprises a plurality of spools of motor winding wire in the oil-filledspace, wherein each of the plurality of spools of motor winding wirecomprises: a conductive core; an electrically insulating polymer layerabout said conductive core; and a contaminant resistant outer polymerlayer about said electrically insulating polymer layer.
 9. The motor ofclaim 1 wherein the electrically insulating polymer layer and thecontaminant resistant outer polymer layer each extend substantiallyalong an entire spooled length of the conductive core.
 10. The motor ofclaim 1 wherein the motor forms a portion of an electrically submersiblepump.
 11. A motor for use within a hydrocarbon wellbore, the motorcomprising: a casing; at least one spool of motor winding wire disposedwithin the casing and comprising: a conductive core; an electricallyinsulating polymer layer about said conductive core; and a contaminantresistant outer polymer layer about said electrically insulating polymerlayer, wherein said outer polymer layer is of a material selected from agroup consisting of an ethylene-tetrafluoroethylene copolymer,polychlorotrifluoroethylene, ethylene chlorotrifluoroethlyene,perfluoroalkoxy resin, fluorinated ethylene propylene copolymer,polytetrafluoroethylene, expanded-polytetrafluoroethylene (ePTFE), anyimproved fluoropolymers, polyethylene, polypropylene, ethylene-propylenecopolymer, poly(4-methyl-1-pentene), and a polyolefin elastomer, andwherein said outer polymer layer is amended with an adhesive functionalgroup to enhance bonding to said insulating polymer layer.
 12. The motorof claim 11 wherein the adhesive functional group is one of maleicanhydride, acrylic acid, carboxyl acid, and silane.
 13. An electricallysubmersible pump assembly for use in a hydrocarbon well and comprising:a pump; a motor configured to operate the pump; an electrical cableexternal of the motor and connected to the motor to electrically powerthe motor, wherein the motor comprises: a casing; at least one spool ofmotor winding wire separate from the electrical cable and disposedwithin the casing and comprising: a conductive core; an electricallyinsulating polymer layer about said conductive core; a contaminantresistant outer polymer layer; and a tie layer disposed between saidinsulating polymer layer and said outer polymer layer to provide bondingtherebetween.
 14. The electrically submersible pump assembly of claim 13wherein said tie layer comprises a base polymer for bonding to one ofsaid insulating polymer layer and said outer polymer layer, said basepolymer selected from a group consisting of a polyimide, polyester,polyesterimide, polyamide-imide, polyamide, poly-ether-ether-ketone,polyethylene terephthalate, polyphenylene sulfide, a self-reinforcedpolyphenylene, polymeric imide, polymeric ester, polymeric ester-imide,polymeric ester-amide, polymeric amide-imide, polymeric urethane, anepoxy, an ethylene-tetrafluoroethylene copolymer,polychlorotrifluoroethylene, ethylene chlorotrifluoroethlyene,perfluoroalkoxy resin, fluorinated ethylene propylene copolymer,polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylenecopolymer, poly(4-methyl-1-pentene), and a polyolefin elastomer.
 15. Theelectrically submersible pump assembly of claim 14 wherein said tielayer further comprises an adhesive functional group for adhering toanother of said insulating polymer layer and said outer polymer layer,said adhesive functional group selected from a group consisting ofmaleic anhydride, acrylic acid, carboxyl acid, and silane.
 16. Theelectrically submersible pump assembly of claim 13, wherein the casingis hermetically sealed and has an oil-filled space, and wherein the atleast one spool of motor winding is disposed in the oil-filled space.17. The electrically submersible pump assembly of claim 13, wherein saidouter polymer layer is of a material selected from a group consisting ofan ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene,ethylene chlorotrifluoroethlyene, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene,expanded-polytetrafluoroethylene (ePTFE), any improved fluoropolymers,polyethylene, polypropylene, ethylene-propylene copolymer,poly(4-methyl-1-pentene), and a polyolefin elastomer, and wherein saidouter polymer layer is amended with an adhesive functional group toenhance bonding to said insulating polymer layer.
 18. An electricallydriven assembly for use at an oilfield and having a motor comprising: ahermetically sealed casing containing an oil-filled space; a motorwinding spool within the oil-filled space of said casing; and a motorwinding wire of said motor winding spool, said motor winding wire havinga conductive core surrounded by an electrically insulating polymerlayer, the insulating polymer layer surrounded by a contaminantresistant outer polymer layer.
 19. The electrically driven assembly ofclaim 18 wherein the outer polymer layer is one of a fluoropolymer and apolyolefin and the insulating polymer layer is of a material selectedfrom a group consisting of a polyimide, polyester, polyesterimide,polyamide-imide, polyamide, poly-ether-ether-ketone, polyethyleneterephthalate, polyphenylene sulfide, a self-reinforced polyphenylene,polymeric imide, polymeric ester, polymeric ester-imide, polymericester-amide, polymeric amide-imide, polymeric urethane, and an epoxy.20. The electrically driven assembly of claim 19 further comprising atie layer disposed between said insulating polymer layer and said outerpolymer layer for bonding therebetween, said tie layer furthercomprising: a base polymer selected from a group consisting of apolyimide, polyester, polyesterimide, polyamide-imide, polyamide,poly-ether-ether-ketone, polyethylene terephthalate, polyphenylenesulfide, a self-reinforced polyphenylene, polymeric imide, polymericester, polymeric ester-imide, polymeric ester-amide, polymericamide-imide, polymeric urethane, an epoxy, anethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene,ethylene chlorotrifluoroethlyene, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene, polyethylene,polypropylene, ethylene-propylene copolymer, poly(4-methyl-1-pentene),and a polyolefin elastomer; and an adhesive functional group selectedfrom a group consisting of maleic anhydride, acrylic acid, carboxylacid, and silane.
 21. The electrically driven assembly of claim 18,further comprising one of an electric submersible pump, a downholetractor, a powered centralizer, a perforation gun, and a sampling tool,and wherein the motor is configured to operate the one of the electricsubmersible pump, the downhole tractor, the powered centralizer, theperforation gun, and the sampling tool.
 22. A motor for use within ahydrocarbon wellbore, the motor comprising: a casing; at least one spoolof motor winding wire disposed within the casing and comprising: asingle conductive core; an electrically insulating polymer layer aboutsaid conductive core; and a contaminant resistant outer polymer layerabout said electrically insulating polymer layer, wherein the outerpolymer layer is of a material selected from a group consisting of anethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene,ethylene chlorotrifluoroethlyene, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene,expanded-polytetrafluoroethylene (ePTFE), any improved fluoropolymers,polyethylene, polypropylene, ethylene-propylene copolymer,poly(4-methyl-1-pentene), and a polyolefin elastomer.
 23. The motor ofclaim 22, wherein the motor is powered by an electrical cable externalof the casing and separate from the at least one spool of motor windingwire.
 24. The motor of claim 22, wherein the casing is hermeticallysealed and has an oil-filled space, and wherein the at least one spoolof motor winding is disposed in the oil-filled space.
 25. A motor foruse within a hydrocarbon wellbore, the motor comprising: a casing; atleast one spool of motor winding wire disposed within the casing andcomprising: a single conductive core; an electrically insulating polymerlayer about said conductive core; a contaminant resistant outer polymerlayer about said electrically insulating polymer layer; and a tie layerdisposed between said insulating polymer layer and said outer polymerlayer to provide bonding therebetween, wherein the outer polymer layeris of a material selected from a group consisting of anethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene,ethylene chlorotrifluoroethlyene, perfluoroalkoxy resin, fluorinatedethylene propylene copolymer, polytetrafluoroethylene,expanded-polytetrafluoroethylene (ePTFE), any improved fluoropolymers,polyethylene, polypropylene, ethylene-propylene copolymer,poly(4-methyl-1-pentene), and a polyolefin elastomer.
 26. The motor ofclaim 25, wherein said outer polymer layer is of a material selectedfrom a group consisting of an ethylene-tetrafluoroethylene copolymer,polychlorotrifluoroethylene, ethylene chlorotrifluoroethlyene,perfluoroalkoxy resin, fluorinated ethylene propylene copolymer,polytetrafluoroethylene, expanded-polytetrafluoroethylene (ePTFE), anyimproved fluoropolymers, polyethylene, polypropylene, ethylene-propylenecopolymer, poly(4-methyl-1-pentene), and a polyolefin elastomer, andwherein said outer polymer layer is amended with an adhesive functionalgroup to enhance bonding to said insulating polymer layer.
 27. The motorof claim 25, wherein the motor is powered by an electrical cableexternal of the casing and separate from the at least one spool of motorwinding wire.